Vilan for VS Code

Vilan is a language for building full-stack web apps. It compiles to JavaScript and runs on Node and in the browser, but it is not JavaScript: values are copied instead of shared, there is no null and no exceptions, await is implicit, and the compiler checks the things you usually find out at runtime.

This extension is the editor half of that toolchain. Everything below is the compiler's own analysis, served by vilan-lsp, the same front end that builds your project, so the editor and the build never disagree.

What you get

Live diagnostics: the compiler's errors as you type, with its notes and help text.
Completion: call-shaped, with the signature and doc comment on the item; scope, member, and import-path positions, plus snippets for fun, struct, for, and match. Configurable down to plain names (vilan.completion.functionCall).
Hover: inferred types on locals and parameters (loan conventions included), doc comments on everything you declared, and documentation on the language's own keywords, deep-linked into the book.
Inlay hints: the inferred types of let bindings and parameters.
Semantic highlighting from the analyzer, over a TextMate grammar (including vilan code fences in Markdown).
Go to definition, including into the std package.
Find references and rename (locals, parameters, fields).
Document outline.
Format Document: vilan fmt's formatter, byte for byte.
Organize Imports: sorts imports into canonical order and prunes unused ones, from the Source Action menu or on save.
A vilan.toml schema: completion and validation in the manifest, for TOML extensions that consume contributed schemas (Even Better TOML).

All of it keeps working while the file has errors: the server analyzes the recovered parse, so a half-typed line does not take your hovers with it.

Getting started

1. Install the toolchain. The extension talks to vilan-lsp, which ships with the compiler. On Linux and macOS:

curl -fsSL https://github.com/vilan-lang/vilan/releases/latest/download/install.sh | sh

On Windows, in PowerShell:

irm https://github.com/vilan-lang/vilan/releases/latest/download/install.ps1 | iex

That puts vilan and vilan-lsp in ~/.vilan/bin (on Windows, %USERPROFILE%\.vilan\bin). The unix script prints the PATH line to add; the PowerShell one adds the directory to your user PATH itself, so open a new terminal afterwards. vilan upgrade updates both later, and every release also carries plain archives if you would rather unpack one yourself.

2. Open a .vl file. The extension starts the server on first open.

Keep the two in step: the extension and the toolchain ship from one repo at one version, and a server older than the extension will not know about newer language features.

Finding the server

The extension runs vilan-lsp from your PATH. If it lives somewhere the editor's PATH does not reach (a checkout's target/release/vilan-lsp, or an install directory you did not add), point vilan.server.path at it (absolute, or a name to resolve on PATH).

The server carries the std sources inside itself, so definitions into std resolve on a machine with nothing else installed. Inside a Vilan checkout it uses that working tree instead; vilan.stdPath overrides both.

Settings

Setting	Type	Default	What it does
`vilan.server.path`	string	`vilan-lsp`	Path to the `vilan-lsp` executable (on `PATH`, or absolute).
`vilan.stdPath`	string	`""`	Path to the `std` source root (`vilan/std/src`). Overrides auto-discovery; sets `VILAN_STD` for the server.
`vilan.inlayHints.enabled`	boolean	`true`	Show inlay type hints. Applies live.
`vilan.semanticTokens.enabled`	boolean	`true`	Use analyzer-based semantic highlighting; when off, the TextMate grammar is used. Applies live.
`vilan.completion.functionCall`	`none` \| `parensOnly` \| `full`	`full`	How completion inserts a function or method call.
`vilan.organizeImports.onSave`	boolean	`false`	Run Organize Imports before each save.

Every setting applies live, with no window reload: the feature toggles are pushed to the running server, and a changed vilan.server.path / vilan.stdPath restarts it for you. (There is also a Vilan: Restart Language Server command, for when you have rebuilt the binary underneath it.)

vilan.organizeImports.onSave is handled by the extension's own on-save hook, so it leaves your editor.codeActionsOnSave untouched. If you would rather drive it through that standard mechanism, leave this off and add "editor.codeActionsOnSave": { "source.organizeImports": "explicit" } instead; organizing is a fixed point, so having both on is harmless.

Pruning is conservative: it never runs while the file has errors, never removes a re-export, and keeps any import that derive-generated code references.

Learning Vilan

The book: guide, tour, and the language specification.
Coming from JavaScript: the differences that will bite first.
The repository, including a working full-stack example app.

Status: fast-moving alpha. The language changes weekly and there are no stability promises yet.

Developing the extension

From a checkout of the repository:

npm install
npm run build      # bundle to out/extension.js

Then press F5 in VS Code to launch an Extension Development Host with the extension loaded, and open a .vl file to activate it. Point vilan.server.path at your target/release/vilan-lsp to test against a local build of the server.

icon.png is a derived asset, not a source: it is a vendored copy of the brand pipeline's baked/icon_256.png, which the private vilan-lang/branding repository bakes from the flat mark. Re-vendor after any change to the mark.

License

MIT or Apache-2.0, at your option; see LICENSE.md. The Vilan logo and icon are covered by their own license instead.